Forty-one patients with NPC underwent T2 mapping and mDIXON Quant imaging for parotid glands before RT, mid-RT, and post-RT. From pre-RT to mid-RT, parotid T2 and FF values increased significantly. From mid-RT to post-RT, parotid T2 value continuously increased, but parotid FF value decreased significantly. Change rate of parotid T2 value significantly correlated with parotid atrophy rate from pre-RT to post-RT. Parotid T2 value and FF value negatively correlated with parotid volume, while parotid T2 value positively correlated with MR scan time point significantly. T2 mapping and mDIXON Quant imaging is useful for noninvasive evaluation of radiation-induced parotid damage.